Early fluorocarbon carpet protectant treatments were typically formulated within cationic surfactant systems. With the advent of the use of anionic compositions to provide stain resistance in the cationic treatment, the problem of tip staining arose. When a carpet, pretreated with a stain resist, is treated with a cationic or cationically dispersed fluorochemical repellant, sometimes localized staining can occur on areas of the carpet fibers where the fluorochemical repellant has been deposited. In the industry, this is termed tip-staining. Tip staining is believed due to residues of cationic material on the carpet, the residues providing staining sites for acid dyes, such as caused by spills of soft drinks colored with the acid dye FDandC Red No. 40.
To address the tip staining problem anionic surfactant systems were developed and employed for carpet soil resists, but such surfactant systems compromised repellency. Kirchner in U.S. Pat. Nos. 5,414,111 and 5,565,564 has described certain polyfluorourethane compounds for providing oil and water repellent properties to a carpet substrate. When these polyfluorourethane compounds were applied to carpet substrates as aqueous dispersions using anionic surfactants, tip staining was not a problem. However, an ideal carpet protectant would exhibit higher levels of repellency, towards both oily and aqueous soils, than is provided by the existing art. With such higher levels of repellency, the soils fail to wet the fibers, and are thus readily removed.
Thus there is a need for carpet protectant formulations that improve repellency without either causing tip-staining or gelling problems, or detracting from the compatibility of anionic formulations. The present invention provides such formulations.
The present invention comprises an aqueous dispersion comprising
A. a partially fluorinated urethane polymer having at least one urea linkage, which compound is the product of the reaction of: (1) at least one organic polyisocyanate containing at least three isocyanate groups; (2) at least one fluorochemical compound which contains per molecule (a) a single functional group having one or more Zerewitinoff hydrogen atoms and (b) at least two carbon atoms, each of which is attached to at least two fluorine atoms; and (3) water in an amount sufficient to react with from about 5% to about 60% of the isocyanate groups in said polyisocyanate;
B. a non-fluorinated cationic surfactant; and
C. a non-fluorinated nonionic surfactant.
Such dispersions provide a high level of oil repellency, water repellency and soil resistance when applied to fibrous substrates such as carpets.
The present invention further comprises a method for providing water and oil repellency to a substrate comprising application to the substrate of a dispersion as described above.
The present invention further comprises a substrate treated with a dispersion as described above.